(1) Field of the Invention
The present invention relates to compounds and processes for ring-opening cyclooligomerization metathesis and ring-closing metathesis of olefins. The compound is a molybdenum or tungsten metal (M) complex which comprises an imido ligand (N—R) bound to the M to provide an M=N—R site, an M=C reaction site wherein the C of the M=C reaction site is tethered to the R of the imido ligand via a substituted carbon or carbon and heteroatom chain containing 1 to 12 carbon atoms to form a ring structure, and two to four ligands (R′) bound to the M to provide two to four M-R′ sites. In particular embodiments, the M-R′ sites include each of the oxygens of a dialkoxide ligand or each of the nitrogens of an η1-pyrrolyl ligand are bound to the M.
(2) Description of Related Art
Olefin metathesis is a reaction which in the presence of various transition metal catalysts, including various metal carbenes, the groups around the double bonds of olefins, are exchanged. This exchange enables a variety of reactions: cross metathesis wherein groups between two acyclic olefins are exchanged, ring-closing metathesis in which a compound with two olefins is converted into a cyclic product, ring-opening metathesis wherein dienes are formed from cyclic and acyclic olefins, ring-opening metathesis polymerization wherein cyclic olefins are polymerized into linear polymers, and acyclic diene metathesis polymerization wherein acyclic dienes are polymerized into linear polymers.
Improvements in the metal-carbene catalysts has led to the widespread use of olefin metathesis in organic synthesis. These improved catalysts are of two types: molybdenum or tungsten carbene catalysts (Schrock's catalyst) and ruthenium carbene catalysts (Grubbs' catalyst).
Schrock's catalyst and metathesis reactions using the catalyst have been described in U.S. Pat. No. 4,727,215 to Schrock; U.S. Pat. No. 5,142,073 to Schrock et al.; U.S. Pat. No. 6,121,473 to Schrock et al.; U.S. Pat. No. 6,316,555 B1 to Schrock et al.; U.S. Pat. No. 6,346,652 B1 to Schrock et al.; and, in published U.S. Patent Application No. 2001/0041778 to McConville et al. Schrock's catalyst and metathesis reactions using the catalyst have also been described in, for example, Totland et al., Macromolec. 29: 6114-6125 (1996); Alexander et al., J. Am. Chem. Soc. 210: 4041-4042 (1998); La et al., J. Am. Chem. Soc. 120: 9720-9721 (1998); Weatherhead et al., J. Am. Chem. Soc. 122: 1828-1829 (2000); Jamieson et al., Organometallics 19: 925-930 (2000); Cefalo et al., J. Am. Chem. Soc. 123: 3139-3140 (2001); Hultzsch et al., Organometallics 20: 4705-4712 (2001); and, Hultzsch et al., Agnew. Chem. Int. Ed. 41: 589-593 (2002).
Grubbs' catalyst and metathesis reactions using the catalyst have been described in U.S. Pat. No. 6,197,715 B1 to Bansleben et al.; U.S. Pat. No. 6,313,332 B1 to Grubbs et al.; U.S. Pat. No. 6,410,664 B1 to Bansleben et al.; U.S. Pat. No. 6,414,097 B1 to Grubbs et al.; U.S. Pat. No. 6,482,908 B1 to Grubbs et al.; U.S. Pat. No. 6,486,279 B2 to Lynn et al.; U.S. Pat. No. 6,504,041 to Grubbs' et al.; U.S. Pat. No. 6,506,704 B1 to Bansleben et al.; and, U.S. Pat. No. 6,515,084 B2 to Grubbs et al.
For both of these catalysts, the carbene is untethered. Therefore, at the end of the reaction, a relatively unstable methylidene, M=CH2, complex is produced which often undergoes rapid decomposition. As a consequence, these catalysts are not reusable. Therefore, reactions in which these catalysts are supported on a solid substrate are less economically viable for many commercial applications than if they were reusable.
In light of the above, to render olefin metathesis reactions more economically viable for commercial applications, there is a need for molybdenum or tungsten carbene catalysts which are reusable.